Digital three-dimensional manufacturing, also known as digital additive manufacturing, is a process of making a three-dimensional solid object of virtually any shape from a digital model. Three-dimensional printing is an additive process in which one or more printheads eject successive layers of material on a substrate in different shapes. Three-dimensional printing is distinguishable from traditional object-forming techniques, which mostly rely on the removal of material from a work piece by a subtractive process, such as cutting or drilling.
The production of a three-dimensional object with these printers can require hours or, with some objects, even days. One issue that arises in the production of three-dimensional objects with a three-dimensional printer is consistent functionality of the ejectors in the printheads that eject the drops of material that form the objects. During printing of an object, one or more ejectors can deteriorate by ejecting the material at an angle, rather than normal, to the ejector, ejecting drops that are smaller than an ejector should eject, or by failing to eject any drop at all. An ejector suffering from any of these operational deficiencies is known as an inoperative or malfunctioning ejector. If the operational status of one or more ejectors deteriorates during object printing, the quality of the printed object cannot be assessed until the printing operation is completed. Consequently, print jobs requiring many hours or multiple days can produce objects that do not conform to specifications due to inoperative ejectors in the printheads. Once such objects are detected, the printed objects are scrapped, restorative procedures are applied to the printheads to restore ejector functionality, and the print job is repeated.
Systems that enable detection of inoperative ejectors while printing have been developed. A system that applies restorative procedures to compensate for inoperative ejectors during object printing would enable the continued production of a properly formed object. In this manner, product yield for the printer would be improved and its printing would be more efficient.